Dear Lifehacker,
My iPhone has been intolerably slow since I upgraded to iOS 4, and while I know I can downgrade to 3.1.3 if I have to, I was wondering if I can do anything to speed things up on iOS 4.

Dear Short,
You're far from alone with this problem (in fact, Apple's officially looking into it), and while we've offered one or two suggestions in the past that might help, your question seems like a good opportunity to take a more detailed look at possible solutions.

Note: The tips below are based on various suggestions we've tried and that other netizens have helped speed up their phones. We've tried each, but can't guarantee they'll work for you.

The Double Hard Reset

The first tip we ran across after upgrading our 3G to iOS 4 was this one from Cult of Mac, which suggested that performing a double hard reset (DHR) can speed up iOS 4 performance. I tried this back in June and didn't notice any significant speed increase, but our intern Lauren claimed to have better luck with it, noticing speed improvements afterwards. In short, the DHR consists of performing a hard reset—that is, holding the Home and Sleep/Wake buttons until your phone restarts—twice. During a hard reset, you'll see the Slide to Power Off screen, the phone will go blank, and then the Apple logo will appear when it restarts; keep the Home and Sleep buttons held down through all of this, until the Apple logo appears.

You won't lose anything by performing the DHR, so it's worth a try. As I said, I never noticed an improvement after a DHR, but a lot of people have claimed success with this method.

Disable Unnecessary Features

The next iOS optimization step we'd try consists of disabling unnecessary features. You can pick and choose which features you're willing to disable. Remember, we're only going off anecdotal evidence from Lifehacker readers and various other 3G users around the internet.

Disable Spotlight Searches: On Thursday, we highlighted a reader tip suggesting that turning off Spotlight search indexing that you don't use can help speed things up. (Open Settings, then go to General -> Home Button -> Spotlight Search and uncheck anything you don't use.) I rarely use Spotlight at all, so I didn't mind switching everything off.

If you're still a loyal iPhone 3G owner and upgraded to iOS 4, you've probably noticed…
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Note: One reader suggested that the DHR will help you see the effects of these adjustments. If it does in fact help, the same probably holds for any of the following adjustments.

Delete Your SMS Messages: Today, our friends from down under at Lifehacker AU suggested that deleting text messages will also improve iOS 4 performance on the 3G. The only problem with this is that the iPhone's SMS backup is kind of lame, so you have to do some work if you want to keep them around. (iTunes does back them up, but it's buried in a file helpfully named 3d0d7e5fb2ce288813306e4d4636395e047a3d28.mddata. Webapps like this one will do the parsing and return a friendlier PDF, XLS, or HTML backup, but you're also uploading your texts to a third party service.)

Start from Scratch

The final possibility involves installing a fresh iOS 4 image (returning to factory settings) but not restoring your backups. If you were to do so, you'd have to re-sync all your media, email, contact, and calendar information manually. Basically it's like setting up a new iPhone from scratch, which is kind of a frustrating option if you've spent any amount of time setting up your iPhone.

To give this one a try, just plug in your iPhone, wait for it to show up in the iTunes sidebar, click on it, then click the Restore button. I tried this option this afternoon, and—at first blush, at least—it's the only option that yielded obvious results for me. Performance still feels sluggish relative to iOS 3, but after syncing back my media, calendar, contacts, and applications, it feels like an improvement. The question remains as to whether or not, in time, it'll end up just as slow as it was when I first upgraded.

Hopefully, after one or more of these adjustments, your phone no longer feels like this:

If you're upset that your iPhone 3G is missing the coolest features of iOS 4—namely…
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With all that said, I've downgraded and upgraded my 3G about four or five times since the iOS 4 release, and each time I upgrade, I quickly remember why I downgraded to begin with. On my 3G, iOS 4 doesn't seem to run fast enough, no matter how much tweaking I do. As I said, though, many Lifehacker readers and iPhone users have had better luck, so my experience isn't necessarily indicative of what you'll experience.

Best of luck!
Lifehacker

P.S. If you've been fighting this battle, whether or not you've succeeded, share your experience in the comments.